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Intraocular pressures and glaucoma
MEDICAL ABSTRACTS Andrew S. Gurwood, O.D.
Intraocular pressures and glaucoma Collaer NC, Zeyen T, Caprioli J. Sequential office pressure measurements in the management of glaucoma. J Glaucoma 2005;14(3):196-200. Intraocular pressure (IOP) is a significant risk factor for the development and progression of glaucoma. Although peak IOP values have often dictated diagnostic decision making, there is now insight into the “range” of diurnal IOP as an independent risk factor for the development and progression of glaucoma. This study reviewed the records of 93 consecutive patients (185 eyes) with a diagnosis of either normal-tension glaucoma (NTG), glaucoma suspect, or primary openangle glaucoma, who demonstrated progressive glaucomatous changes to the disc or field despite IOPs that were considered acceptable according to a statistically normal range. All patients were scheduled for daylong, sequential IOP measurements performed every hour between 7 AM and 5 PM on a single day. Additionally, for the patients with NTG, a questionnaire was used to assess the potential for the presence of vasospastic entities such as migraine and Raynaud’s phenomenon. The trend in all subgroups identified higher IOP in the morning, a decrease in the afternoon, and a tendency to increase again at the end of the day. A peak IOP greater than 21 mmHg was seen in only 3% of eyes. However, a range of IOP greater than 5 mmHg was seen in 35% of eyes. In the NTG group, there was a significant correlation between visual field deterioration and both the peak and range of IOP measurements. Additionally, there was
a positive association between NTG and vasospastic conditions. This begs the question: which IOP value is more important? Is it the mean IOP, the peak IOP, the trough IOP, or the range of IOP? The apparent conclusion of this study is that the IOP range throughout a 25-hour period may be more important than the peak value measured within that cycle itself, particularly in those patients who are being treated and seemingly under “control” yet demonstrating progression. This underscores the importance of sequential IOP measurements or at least obtaining IOP readings at different times of day. This would be most important for those patients exhibiting progression despite what appears to be adequate “control.” The study supports the philosophy that when treating patients with glaucoma, therapies should be chosen that allow for flattening of the 24-hour IOP curve. Joseph Sowka, O.D. doi:10.1016/j.optm.2006.01.011
OCT and UBM to detect narrow anterior chamber angles Radhakrishnan S, Goldsmith J, Huang D, et al. Comparison of optical coherence tomography and ultrasound biomicroscopy for detection of narrow anterior chamber angles. Arch Ophthalmol 2005;123(8):1053-9. Laser peripheral iridotomy has made acute-angle closure glaucoma a preventable problem. Some patient populations such as the Native American population of Alaska, as well as Asians and moderate to high hyperopes, have
1529-1839/06/$ -see front matter © 2006 American Optometric Association. All rights reserved.
Andrew S. Gurwood, O.D. higher rates of angle closure than the general population. Early detection in these high-risk patients can lead to prophylactic procedures that can prevent the painful symptoms and potential loss of vision associated with acute angle closure. The most widely utilized technique used to determine the risk of angle closure is gonioscopy. Unfortunately, this technique is based on a subjective assessment of the patient’s anatomy. Ultrasound biomicroscopy (UBM) is an instrument capable of rendering high-resolution images of the anterior chamber angle. However, this instrument is not practical for the private practitioner, because it requires the patient to be in a supine position with an immersion bath placed on the eye. The procedure is time consuming, and results are dependent on the operator’s skill. Optical coherence tomography (OCT) is a technology that utilizes light rather than sound to obtain
Intraocular pressures and glaucoma Collaer NC, Zeyen T, Caprioli J. Sequential office pressure measurements in the management of glaucoma. J Glaucoma 2005;14(3):196-200. Intraocular pressure (IOP) is a significant risk factor for the development and progression of glaucoma. Although peak IOP values have often dictated diagnostic decision making, there is now insight into the “range” of diurnal IOP as an independent risk factor for the development and progression of glaucoma. This study reviewed the records of 93 consecutive patients (185 eyes) with a diagnosis of either normal-tension glaucoma (NTG), glaucoma suspect, or primary openangle glaucoma, who demonstrated progressive glaucomatous changes to the disc or field despite IOPs that were considered acceptable according to a statistically normal range. All patients were scheduled for daylong, sequential IOP measurements performed every hour between 7 AM and 5 PM on a single day. Additionally, for the patients with NTG, a questionnaire was used to assess the potential for the presence of vasospastic entities such as migraine and Raynaud’s phenomenon. The trend in all subgroups identified higher IOP in the morning, a decrease in the afternoon, and a tendency to increase again at the end of the day. A peak IOP greater than 21 mmHg was seen in only 3% of eyes. However, a range of IOP greater than 5 mmHg was seen in 35% of eyes. In the NTG group, there was a significant correlation between visual field deterioration and both the peak and range of IOP measurements. Additionally, there was
a positive association between NTG and vasospastic conditions. This begs the question: which IOP value is more important? Is it the mean IOP, the peak IOP, the trough IOP, or the range of IOP? The apparent conclusion of this study is that the IOP range throughout a 25-hour period may be more important than the peak value measured within that cycle itself, particularly in those patients who are being treated and seemingly under “control” yet demonstrating progression. This underscores the importance of sequential IOP measurements or at least obtaining IOP readings at different times of day. This would be most important for those patients exhibiting progression despite what appears to be adequate “control.” The study supports the philosophy that when treating patients with glaucoma, therapies should be chosen that allow for flattening of the 24-hour IOP curve. Joseph Sowka, O.D. doi:10.1016/j.optm.2006.01.011
OCT and UBM to detect narrow anterior chamber angles Radhakrishnan S, Goldsmith J, Huang D, et al. Comparison of optical coherence tomography and ultrasound biomicroscopy for detection of narrow anterior chamber angles. Arch Ophthalmol 2005;123(8):1053-9. Laser peripheral iridotomy has made acute-angle closure glaucoma a preventable problem. Some patient populations such as the Native American population of Alaska, as well as Asians and moderate to high hyperopes, have
1529-1839/06/$ -see front matter © 2006 American Optometric Association. All rights reserved.
Andrew S. Gurwood, O.D. higher rates of angle closure than the general population. Early detection in these high-risk patients can lead to prophylactic procedures that can prevent the painful symptoms and potential loss of vision associated with acute angle closure. The most widely utilized technique used to determine the risk of angle closure is gonioscopy. Unfortunately, this technique is based on a subjective assessment of the patient’s anatomy. Ultrasound biomicroscopy (UBM) is an instrument capable of rendering high-resolution images of the anterior chamber angle. However, this instrument is not practical for the private practitioner, because it requires the patient to be in a supine position with an immersion bath placed on the eye. The procedure is time consuming, and results are dependent on the operator’s skill. Optical coherence tomography (OCT) is a technology that utilizes light rather than sound to obtain